We are using solar energy to generate hot and pressurised ‘supercritical’ steam, at the highest temperatures in the world, outside of fossil fuel sources.

The challenge

Increasing the efficiency of solar electricity

A supercritical steam demonstration at our solar field.

A supercritical steam demonstration at our solar field.

Commercial solar thermal power plants around the world use subcritical steam, operating at similar temperatures but at lower pressure. If these plants were able to move to supercritical steam, it would increase the efficiency and help to lower the cost of solar electricity.

Supercritical solar steam is water pressurised at enormous force and heated using solar radiation. Around 90 per cent of Australia's electricity is generated using fossil fuel, but only a small number of power stations are based on the more advanced supercritical steam.

Our response

Delivering solar breakthroughs through collaboration

We have been developing advanced solar storage to provide solar electricity at any time, day or night through a $5.68 million research program supported by the Australian Renewable Energy Agency (ARENA) and a broader collaboration with Abengoa Solar, the largest supplier of solar thermal electricity in the world.

The breakthrough was made at the CSIRO Energy Centre, Newcastle, home to Australia’s low emission and renewable energy research. The Centre includes two solar thermal test plants featuring more than 600 mirrors (heliostats) directed at two towers housing solar receivers and turbines.

[Music plays and text appears: Supercritical solar steam: the new frontier for power generation]

[Image changes to show an array of mirrors reflecting sunlight onto a solar tower and then moves to show moving solar panels]

Mike Collins: Solar thermal energy works by concentrating sunlight using mirrors. The light is then shone up on top of the tower where there’s a solar receiver and in that receiver there’s a panel of tubes which steam is flowing inside. That steam is heated to high temperatures and then it flows back down the tower to a turbine at the bottom of the tower, a steam turbine. The steam flowing through that turbine spins the generator to generate electricity.

Robbie McNaughton: The temperatures that we’ve obtained are over 550 degrees and at pressures above 24 mega Pascals. This is called supercritical steam generation and it’s a state where steam actually transforms without boiling.

[Camera moves back to the solar panels and solar boiler]

The steam conditions that we’ve achieved are comparable to what is running at the moment in fossil fuel power stations. So we’re able to actually either displace the steam that goes into these, reducing the fossil fuel reliance, or in some cases maybe even replace fossil fuel completely.

[Image has changed back to Robbie]

It’s really exciting to work on these types of projects. Doing a world first is always exciting but in this case what we’ve actually been able to do is potentially make a step change in the way solar thermal power is generated.

The results

Bringing zero emission energy closer

Instead of relying on burning fossil fuels to produce supercritical steam, this breakthrough demonstrates that the power plants of the future could instead be using the free, zero emission energy of the sun to achieve the same result.

Although there is still work to be done before this technology is ready for commercialisation, ARENA CEO Ivor Frischknecht acknowledged the significant achievement saying it 'brings solar thermal energy a step closer to cost competitiveness with fossil fuel generated power.'

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